The present invention relates to counting and measuring devices and, more particularly, to a liquid crystal display capable of dynamically displaying barcodes and being read by conventional barcode scanning devices.
There are many requirements in various areas of industry, transportation, warehousing, marketing, and the like for counting and measuring for asset identification and tracking, inventory control, and other functions. Such counting or measuring is typically recorded and forms the basis for charging customers for goods or services delivered or reporting on current inventory on hand or at various stages of manufacturing.
In the utility industry, the count or measurement is typically the number of gas, water, or electric power units delivered to a given customer. In chemical manufacturing processes, the measurement could be the volumes units of a bulk material moved from one process stage to the next. Additionally, it may be desirable to record process state variables at various time intervals, such as pressure, temperature, elapsed time in a process stage, or the like. In transportation, counted units or measured weights are transported over measured distances. And so forth.
In the past, counts and measurements were typically recorded manually and transferred from report to report manually. Such methods of recording counts and measurements are prone to entry or transcription errors which can result in overcharges or undercharges to customers, reduced quality in manufactured goods, and often costly remedial actions to compensate for the errors.
Great strides have been made in overcoming accuracy problems in many areas involving counting and tracking of assets, most notably in inventory identification and tracking, through the use of automatic identification mechanisms such as barcodes along with computerized inventory tracking systems. Barcode technologies have been most successfully applied to circumstances dealing with discrete articles which can be labelled with a barcode and then optically scanned upon entering an inventory and also upon leaving, such as through sale of the products. In stores, the scanning of barcoded merchandise speeds up the check out process and increases its accuracy since the price of the item can be called up by the system upon scanning rather than entered manually. Additionally, inventory can be updated concurrently by decrementing the inventory count of an item when it is scanned for sale.
Instruments which automatically record counts or measurements are known which either store a value or transmit a value to another device such as a computer or a readout device. In general, there are few instruments which can indicate a value or count and which can be queried with a separate device, other than those which use transponders or to which an electrical or mechanical connection must be made. Exceptions to this are disclosed in U.S. Pat. Nos. 5,171,976 and 5,270,522 issued on Dec. 15, 1992 and Dec. 14, 1993 respectively to the present inventor. These patents disclose dynamic barcoded metering devices, such as barcoded odometers, which can be optically scanned. The term "dynamic barcode" refers to the capability of these devices to change the displayed barcode to indicate a current reading. U.S. Pat. Nos. 5,171,976 and 5,270,522 are incorporated herein by reference.
Although dynamic barcoded odometers have utility in many applications, odometers are not appropriate for all applications. U.S. Pat. Nos. 5,171,976 and 5,270,522 make general references to dynamic barcoded liquid crystal display devices in which the displayed barcode is altered electronically, according to a currently sensed count or measurement.
Conventional barcode patterns are made up of combinations of thick and thin "bars" or linear elements, such as thick and thin dark bars combined with thick and thin light bars or separations. Some barcodes have multiple bar thicknesses. Each alphanumeric symbol to be represented is associated with a unique barcode pattern. The barcode pattern is typically read by a laser scanner device which scans a laser beam across the pattern and detects reflections from the pattern using a photosensitive device. Sensed reflections from the barcode elements are used to generate pulses having pulse lengths proportional to the thicknesses of the bars. Timing circuits within the scanning device measure the width of the pulses and spaces therebetween which are, in effect, negative barcode elements. Logic circuitry within the scanner associates the detected pulse patterns with the corresponding characters. A scanner may scan a pattern multiple times to increase accuracy. If the scanned pattern does not correspond to a known character, an error condition is indicated.
Many barcode "symbologies" have been developed and have characteristics which are appropriate for particular applications. Barcode symbologies fall into two general categories: discrete symbologies and continuous symbologies. In a discrete code, each character can stand alone and can be decoded independently from adjacent characters. Each character is separated from the adjacent characters by loosely toleranced intercharacter gaps which contain no information. Every character has a bar at each end. A continuous code has no intercharacter gaps. Every character starts with a bar and ends with a space. The end of one character is indicated by the start of the next. An example of a common discrete code is Code 39 which can represent alphabetic, numeric, and control characters. A commonly used continuous code is Universal Product Code (UPC) which is a numeric only code used widely in the marking of consumer products.